Is there anything in the bible that you know of that they base this belief on? Because it seems really assumptive.
I can't think of anything in the bible on which they base this belief...
It looks like Mary Baker Eddy (Christian Scientist) could have possibly just made it up:
As she "searched Scripture" she wrote down her discoveries and insights, forming a complete system of "theology" all her own---an astonishing mixture of primitive psychology, New England Transcendentalism (especially Emerson and Thoreau), a few accidentally discovered truths, and what we today would call "positive thinking," self-hypnosis, and a smattering of New Age ideas.
These writings were revised and refined throughout her life and, under the title Science and Health, became the supplementary scriptures of Christian Scientists. Mrs. Eddy (or "Mother Eddy," as she came to be called by her devoted followers) was in fact from a worldly standpoint--a rather remarkable thinker far in advance of her time and more "acceptable" in our own pluralistic age. In other ways, however, she was very much a product of her own time and place. She knew about the "adventist'' fever that had swept America, and towards the end of her life quite seriously observed:
'It is authentically said that one expositor of Daniel's dates [in the Old Testament] fixed the year of 1866 or 1867 for the return of Christ....It is a marked coincidence that those dates were the first two years of my discovery of Christian Science ....
Some modern exegesis on the prophetic Scriptures cites 1875 as the year of the second coming of Christ. In that year the Christian Science text-book, Science and Health with Key to the Scriptures, was first published (quoted in Edwin Dakin's Mrs. Eddy: The Biography of a Virginal Mind).
Usually she referred to herself simply as the "discoverer" (one of the titles her Church later gave her) of the "science" of healing.
She sincerely believed her writings to be divinely inspired, and second only to the Sacred Scriptures.(roca.org)
Some more info:
Christian Science, officially called the Church of Christ, Scientist, is a Christian-based faith that emphasizes physical healing through prayer and a recognition of the nonexistence of matter and illness. Date founded: 1879
Place founded: Massachusetts, USA
Founder: Mary Baker Eddy (1821-1910)
Adherents: 150,000 - 400,000 worldwide (see Adherents.com for details)
The Church of Christ (Scientist) was founded by Mary Baker Eddy (1821-1910), a semi-invalid who, in 1862, began to learn from Phineas Quimby the possibility of cures without medicine. In 1866 (the year Quimby died), she suffered a severe injury after a fall on ice, and claimed a complete cure without the intervention of medicine. She was reading an account of one of Jesus' healings in the Bible when she suddenly realized that healing comes by spiritual means, and she was instantly cured.
Eddy thereafter devoted herself to the recovery of the healing emphasis in early Christianity, and in 1875 she completed the first edition of her major book, Science and Health with Key to the Scriptures. In 1879, the Church of Christ (Scientist) was incorporated with the purpose of 'commemorating the word and works of our Master'. She became chief pastor of the Mother Church, and wrote The Manual of the Mother Church to govern its affairs. She is referred to as Mrs. Eddy by church members.
At the end of the 20th century, the church had about 2,500 congregations in 70 countries; its headquarters is at the Mother Church in Boston.
The main texts of Christian Science is the Christian Bible and Eddy's Science and Health with Key to the Scriptures. Both texts are read in Sunday services and studied in private devotions.
Like mainstream Christianity, Christian Science teaches the existence of an all-powerful God and the authority and inspiration of the Bible. Christian Scientists also believe the crucifixion and resurrection of Jesus to be essential to human redemption. Mrs. Eddy taught belief in one God and described God with the synonyms: Principle, Soul, Mind, Spirit, Life, Truth, and Love. Christian Science also departs from traditional Christianity in several doctrines.
The fundamental distinctive teaching of Christian Science is that creation is entirely spiritual and perfect and matter does not exist. Sin, sickness and death also do not exist; we only think they do. "The only reality of sin, sickness, or death is the awful fact that unrealities seem real to human, erring belief, until God strips off their disguise" (Science and Health, 472:27-29).
According to Christian Science, humans are subject to the laws of matter only so long as we believe they are real. So just as in The Matrix Neo could mentally bend a spoon by realizing "there is no spoon," so Christian Scientists can heal themselves spiritually by realizing illness does not exist. (Note: This is a ReligionFacts analogy, not a Christian Science one.)
These core teachings are encapsulated in the "Scientific Statement of Being," which is read at every church service:
There is no life, truth, intelligence, nor substance in matter.
All is infinite Mind and its infinite manifestation, for God is All-in-all.
Spirit is immortal Truth; matter is mortal error.
Spirit is the real and eternal; matter is the unreal and temporal.
Spirit is God, and man is His image and likeness.
Therefore man is not material; he is spiritual. (S&H 468)
Christian Scientists refer to God as "Father-Mother" rather than the biblical "Father." Though unconventional, this is not a major departure from mainstream Christianity, since God is believed to encompass both male and female (both were created "in the image of God").
Christian Science teaches that Jesus is divine but not God, and that Jesus' human nature is a separate entity from the divine Christ. "Jesus Christ is not God, as Jesus himself declared, but is the Son of God" (Science and Health, 361:12-13). "Jesus is the name of the man who, more than all other men, has presented Christ, the true idea of God, healing the sick and sinning and destroying the power of death" (Science and Health, 473:10-17).
Mary Baker Eddy taught that the Holy Spirit is equivalent with "divine Science," i.e., the teachings of Christian Science. "In the words of St. John: ‘He shall give you another Comforter, that he may abide with you forever.’ This Comforter I understand to be Divine Science." (Science and Health, 55:27-29) "His [Jesus'] students then received the Holy Ghost. By this is meant, that by all they had witnessed and suffered, they were roused to an enlarged understanding of divine Science, even to the spiritual interpretation and discernment of Jesus’ teachings and demonstrations, which gave them a faint conception of the Life which is God" (Science and Health, 46:30-47:3).
Mrs. Eddy rejected the traditional doctrine of the Trinity, saying that it suggests polytheism (Science and Health, 256:9-11). She did, however, accept the threefold nature of God, defining it as a trinity of "Life, Truth, and Love," or "God the Father-Mother, Christ the spiritual idea of sonship, and divine Science or the Holy Comforter" (Science and Health 331:26-332:3).
Eddy defined salvation as follows: "Life, Truth, and Love understood and demonstrated as supreme over all; sin, sickness and death destroyed" (Science and Health, 593:20-22).
Heaven and hell are states of mind. Heaven is "not a locality, but a divine state of Mind in which all the manifestations of Mind are harmonious and immortal" (Science and Health, 291:13-16). It is "Harmony; the reign of Spirit; government by the divine Principle; spirituality; bliss; the atmosphere of Soul." (Science and Health, 587:25-27). Hell is "Mortal belief; error; lust; remorse; hatred; revenge; sin; sickness; death; suffering and self-destruction; self-imposed agony; effects of sin; that which 'worketh abomination or maketh a lie.'" (Science and Health, 588:1-4).
Christian Science has no creed, but Eddy listed six "important points, or religious tenets" in Science and Health (496) as follows:
As adherents of Truth, we take the inspired Word of the Bible as our sufficient guide to eternal Life.
We acknowledge and adore one supreme and infinite God. We acknowledge His Son, one Christ; the Holy Ghost or divine Comforter; and man in God's image and likeness.
We acknowledge God's forgiveness of sin in the destruction of sin and the spiritual understanding that casts out evil as unreal. But the belief in sin is punished so long as the belief lasts.
We acknowledge Jesus' atonement as the evidence of divine, efficacious Love, unfolding man's unity with God through Christ Jesus the Way-shower; and we acknowledge that man is saved through Christ, through Truth, Life, and Love as demonstrated by theGalilean Prophet in healing the sick and overcoming sin and death.
We acknowledge that the crucifixion of Jesus and his resurrection served to uplift faith to understand eter- nal Life, even the allness of Soul, Spirit, and the nothingness of matter.
And we solemnly promise to watch, and pray for that Mind to be in us which was also in Christ Jesus; to do unto others as we would have them do unto us; and to be merciful, just, and pure. (religionfacts.com)